Which Equation Should Be Used for Finding Maximum Constant Deceleration?

[sandman203]

Homework Statement

Hi all this is just a quickie, but in one of my texts a question asks to find the maximum constant deceleration given an initial speed, time to stop and the distance it took.

Now I am not sure whether to use v = u + at or s = 1/2at^2 + ut

im thinking more v = u + at becuase I am not given displacement, I am given a distance.. any thoughts? cheers!

 

[CWatters]

Do both give the same answer?

 

[rcgldr]

If it's constant acceleration, and the given inputs are the initial speed and time to stop, there there is only one possible constant acceleration (deceleration). The maximum and minimum would be the same. I'm not sure why that was mentioned. It the distance to stop is also given, it either corresponds to the time, or else there's a conflict in the problem statement.

 

[SteamKing]

Why would you think, in this case, that displacement is not equal to distance?

 

[Nickie]

As a scientist, it is important to carefully consider the equations and variables involved in a problem before deciding on the appropriate equation to use. In this case, since you are given the initial speed, time to stop, and distance, it would be more appropriate to use the equation v = u + at. This equation relates the final velocity (v), initial velocity (u), acceleration (a), and time (t), which are all given in the problem. Using this equation, you can solve for the maximum constant deceleration. It is always important to check that the units of your final answer are consistent with the units of acceleration (m/s^2). I hope this helps. Good luck with your homework!